MODIFICATION OF DRUG RESISTANCE

根治性化疗的主要障碍之一是多种药物 抗性(MDR)，先天的或后天的。对阿霉素(DX)的耐药性可能 与膜P-糖蛋白(PGP-170)的过度表达有关， 和/或其他机制，并可能涉及多重耐药(MDR)。 多药耐药逆转的研究主要是利用高耐药的细胞。 体外，对MDR中的细胞异质性知之甚少，或 MDR逆转过程中的细胞异质性。这个项目的目标是 在亚群中确定与DX体外耐药相关的因素 从肿瘤分级程度不同的人群中分离出的肿瘤细胞 抗性，以开发它们的调制方法。获得的知识 来自体外的结果将被应用于体内来评估这种可能性 通过治疗来克服抵抗力。为此，老鼠和人类 细胞系。(P388、Kb HeLa和卵巢癌A2780)，亚系 对阿霉素的分级耐药程度已被表征为 在体外并建立了在体内生长的机制。虽然P388、KB和A2780细胞 分级表达PGP-170，HeLa细胞为 无Pgp-170过度表达的多药耐药。分离细胞 具有特定的抗性机制，例如过表达PGP-170 和减少DX蓄积，流式细胞仪，FACSTAR，将被使用；细胞 将评估亚种群的个体集落形成(ICFA) 细胞生长的异质性和DX敏感性 调节剂，DMDP，一种新的钙通道阻滞剂，和潘生丁，a 核苷转运抑制剂将是有待研究的调节剂。 与维拉帕米不同，DMDP的有效体外浓度可能是 在体内实现了无宿主毒性。这样做的具体目的是 建议是：确定对DX的反应和耐药性的决定因素 在整个细胞群体和MDR分级程度的子集中；2) 为了定义调节剂的时间表和有效的非细胞毒性剂量， 双嘧达莫和钙通道阻滞剂DMDP需要逆转 分级抗性水平和机制以及(3)在体内建立 模拟在体外发现的最佳条件的模型系统，以便 评价地塞米松治疗反应和选择性的多样性 与调节剂联合对抗耐DX的细胞。这些数据 应为制定有针对性和更具选择性的规定提供依据 肿瘤的治疗表现出多药耐药的特点。

One of the major obstacles to curative chemotherapy is multidrug resistance (MDR), innate or acquired. Resistance to doxorubicin (DX) may be associated with overexpression of membrane p-glycoprotein (PGP-170), and /or other mechanisms, and may involve multiple drug resistances (MDR). Reversal of MDR has been studied mostly with highly resistant cells in vitro, and little is known about cellular heterogeneity in MDR, or cellular heterogeneity in reversal of MDR. The goal of this project is to identify factors associated with the in vitro resistance to DX in subsets of tumor cells isolated from populations with graded degrees of resistance, to develop approaches for their modulation. Knowledge gained from in vitro results will be applied in vivo to evaluate the possibility of overcoming resistance therapeutically. To this end, mouse and human cell lines. (P388, KB HeLa and ovarian carcinoma A2780), and sublines of graded degrees of resistance to adriamycin, have been characterized in vitro and established to grow in vivo. Although P388, KB and A2780 cells express PGP-170 in graded degrees, HeLa cells provide the model for multidrug resistance without overexpression of PGP-170. To isolate cells with a specific mechanism of resistance, e.g. overexpression of PGP-170 and decreased DX accumulation, flow cytometry, FACSTAR, will be used; cell subpopulations will be assessed for individual colony formation (iCFA) cellular heterogeneity in growth and DX sensitivity with and without the modulators, DMDP, a new calcium channel blocker, and dipyridamol, a nucleoside transport inhibitor will be the modulators to be studied. Unlike verapamil, effective in vitro concentrations of DMDP could be achieved in vivo without host toxicity. The specific aims of this proposal are: to identify determinants of response and resistance to DX in whole cells populations and in subsets with graded degrees of MDR; 2) to define the schedule and effective noncytotoxic doses of the modulator, dipyridamol and a calcium channel blocker, DMDP, required to reverse graded levels and mechanisms of resistance and (3) to establish in vivo model systems mimicking the conditions found optimal in vitro, in order to evaluate the diversity in therapeutic response and selectivity of DX in combination with the modulator against cells resistant to DX. These data should provide a basis for the development of specific and more selective treatments of tumor exhibiting multidrug resistance characteristics.